Visual cortex is the site at which dramatic transformations in neuronal receptive field properties - and thus the representation of the visual world - occur. One important transformation is the integration of inputs from the right and left eyes (binocularity), which provides the basis for the representation of the visual world in three dimensions. The excitatory input that individual cortical neurons receive from the visual thalamus is segregated into right and left eye channels. While it is clear that visual cortex is the site at which these two streams of information converge for the first time, the roles that afferent excitation, cortical inhibition and spike threshold all play in creating a three- dimensional representation - stereo vision - are as yet unknown. Using whole cell recordings in vivo, I will investigate the emergence of binocularity and the contributions of these three mechanisms. The development of stereovision is sensitive to the visual environment: disruptions early in life, such as eye misalignment (strabismus), lead to persistent stereo deficits. Early strabismus causes cortical neurons to become highly monocular in their spiking response profiles. The effect of strabismus on the inputs to the cortical neurons is unknown. I will examine whether latent inputs exist in strabismic animals, which will allow me to determine if the changes in cortical cell responses are due to an anatomical reorganization of afferents or a physiological modulation that leaves latent inputs intact and potentially recoverable. PUBLIC HEALTH RELEVANCE: Visual cortex is the site at which inputs from the right and left eyes are first integrated to provide a basis for the representation of the visual world in three dimensions (stereo vision). Proper stereo vision is disrupted by a difference in acuity between the two eyes (anisometropia) or misaligned eyes (strabismus) occurring during development. By understanding the mechanisms underlying both normal and abnormal visual function, we will gain insight into how normal vision may be restored in patients with related visual deficits.